Abstract (Intravital Core) Advances in optical imaging technologies have equipped researchers with extremely powerful tools to uniquely address clinically and biologically important questions that can only be accomplished in whole organ studies. Multi-photon intravital microscopy offers the investigator a minimally invasive yet high resolution technique with increased depth of penetration and markedly reduced phototoxicity for visualization of integrative organ physiology at the cellular level. Researchers equipped with these unique and ever improving tools can utilize optical microscopy and digital image analysis to study subcellular events, cell-cell interactions, biochemistry, and molecular and cellular biology. This has greatly enhanced the understanding of physiologic and disease processes, developmental biology, and has hastened and improved the reliability and interpretation of preclinical data. A tremendous strength of the present O'Brien Center is our ability to customize the optical approach to individual user's needs. The Intravital Microscopy Core provides an extensive range of services including access to the necessary ICBM facilities for use and expertise in all aspects of intravital optical imaging from training at the hands-on level to the theoretical aspects of optical microscopy, cell and molecular biology, and kidney systems physiology.